1. Field
The present invention relates to an electrophoretic particle, an electrophoretic particle dispersion liquid, a display medium, and a display device.
2. Description of the Related Art
Electrophoretic display media are extensively studied as displays having an image-retaining property (what is called a memory property). In these display systems, display is effected by using charged electrophoretic particles in a liquid and alternately moving the electrophoretic particles to the visual field and the rear field in the cell (having the constitution of superposed two electrode substrates, and the electrophoretic material enclosed together with a dispersion medium between the two electrode substrates) by the application of electric field.
For example, JP-A-2005-227729 (the term “JP-A” as used herein refers to an “unexamined published Japanese patent application”) proposes “a charge controlling method of controlling the charging state of particle by introducing to the surface of the particle an organic group having a main structure and a substituent bonding to the main structure, and setting at least one condition of the kind of the substituent, the number of bonds to the main structure and the bonding position, to localize electrons in the main structure to thereby control the charging state of the particle” and “for the main structure to have a part where π electrons are delocalized”.
JP-A-2006-106596 proposes “particle for a display medium constituting the display medium for use in a panel for information display to display information by enclosing the display medium between two substrates, at least one of which is transparent, and moving the display medium by the application of an electric field to the display medium, wherein the surface of the particle for the display medium for use in the panel for information display is covered with silica fine particle having a particle size of 450 nm or less by a sol/gel method,” and also proposes “to perform surface treatment with a melamine resin for the application of quantity of charge”.
JP-A-2009-223080 proposes “a chargeable particle which is obtained by the direct amido-bonding of a carboxyl group of a particle having the carboxyl group and an ethyleneoxy group on the surface thereof to an amino group of a compound having the amino group and a functional group, in the presence of a condensing agent, wherein the amido group having a functional group and the prescribed ethyleneoxy group are directly bonding to the surface of the chargeable particle”.